Blind stitch mechanism



Sept. 30, 1941 1 F ARVER 2,257,363

BLIND STITCH MECHANISM Filed April l, 1958 2 Sheets-Sheet l Tra/wma* Sept. 30, 1941.

.1. F. ARvl-:R 2,257,363

BLIND S TITCH MECHANI SM Filed April l, 1938 2 Sheets-Sheet 2 Patented Sept. 30, 1941 UNITED STATES PATENT OFFICE BLIND- s'rrrrvrsacHANIsM Y t stitch Company, St. Paul, Minn., a copartnership composedv of Joseph F. Arver and Harold E. Ruttenberg Application April` 1, 193s', seriaiNo. 199,397V

` (ci. i12-17s) 4 Claims.

`This invention relates to blind-stitch mechanisms for sewing machines and comprises a device detachably connected to the presser foot bar and needle bar of a sewing machine and an improved plunger, all adapted to coordinate with the cloth feeding mechanism of a sewing machine to produce so-called blind-stitches well known in the art.

` This device includes distinct and advantageous improvements over my United States patent ape plication Ser. No. 110,469, filed Nov. 12, 1936.

As in my said previous application this device employs a horizontally reciprocating needle action and is designed for high speed machines andl silent action, as hereinafter fully set forth and illustrated in the accompanying drawings, in which:

Fig. 1 is a top view of myimproved blind stitcher mounted on the presser foot bar and connected with the needle bar of a sewing machine, and showing a portion of the sewing vmachine table at and around the cloth plate.

Fig. 2 is a front elevation of the stitcher de-v Viceshown in Fig. land those parts below the stitcher in longitudinal section .as on line `2-j--2 in Fig. 1.

` Fig. 3 is a left end elevation of Fig. 2. Fig. 4 is a `vertical longitudinal section of my improved cloth raising and guiding plunger and Fig. 5 is a right side elevation of Fig. 4. Fig. 6 is a per- I spective, enlarged detail view of a piece of lgoods and a row of blind stitches as made by this device.

Fig. 'l is a perspective View of the fcotplate' of my attachment, its needle retaining slide' and certain associated parts on the plate, the needle positioned to start penetration of goods. Figs. 8` to 13 inclusive show in progressive ordervarious steps or conditions in making blind stitches in a piece of goods, these views showing mainly the' needle action, thread manipulation and forma-v tion of thread loops by the looping member ofV the device. Fig. 14 is a section of the mechanism .in horizontal plane as on line Iii-'I4 inFig. 2

revealing mainly the link construction transmitting power from the vertical needle bar to produce presser foot of the machine. 4 is the usual removable cloth plate of the table which in this case is of special construction. l f

' 5 `(in Figs. 2 and 3) is the lower and outer end part ofa sewing machine head from which project downwardly the usual presser foot bar 6 and needle bar 7. My device utilizes the vertical reciprocating action of the needle bar to provide horizontal reciprocation of the needle in a plane parallel to table II and directly over its plate 4. The needle action provides successive penetrations of cloth 2 which is fed rearwardly on the cloth plate by the usual feed bar 8 reciprocable under the cloth plate and raised in proper timing to contact and move the cloth rearwardly by meansV of the usual feed dog (not shown) well known in the art.

Said feed bar, its timing and manipulation are well"` known i-nthe art but mentioned herein for the purpose of revealing theirfunction with relation to my stitcher means. As stated the cloth feeding means may be of the usual construction but it is preferred to use in conjunction with this device the feeding mechanism fully disclosed in myrpatent application Serial No. 110,469.

This mechanism comprises a main frame, or presser foot member, comprising an L shaped frame of' which the vertical part is designated 9A` securalole removably as at 9B to the lower and exposed end of thesewing machine presser foot bar 6 and part 9 comprises an integral base of elongated quadrangular shape normally close to and parallel with the cloth plate 4 and elongated in direction of the sewing machine head 5.

The sewing machine needle bar 'IV is parallel to and forward of the upright 9A of the' frame. Between it and the frame part 9A is positioned an I.- shaped oscillatable lever I0 -(mounted on a pin It)` normally in position with its longer arm slotted as at IUS and extending in an inclined plane traversing the vertical path of the needle bar. Said slot is slidably engaged' by a cross head I I'which in turn is pivotally connected to a block I2 suitably fixed on the lower end of the needle bar 1. The right or lower and outer end of the main lever is pivoted at I3 to the frame part 9A to the right of the needle bar (see Figs. 2 and 3) Below the convergence of the arms of lever I0 is yprovided afixed forwardly directed pin I4 pivotally engaging the left end of a horizontally directed link 2| (see Figs. 14 and 2). The right end of said link is pivotally connected at I5 to an L-shaped elongated vertical fiange I'6 fixed as at I`I-A on the right hand end part of a reciprothrough which extends downwardly under tension, a thread 25 (from any suitable source of supply as provided for on sewing machines) said thread under continuous light tension and below said aperture extending alongside the rear side of the needle to its eye through which the thread extends horizontally forward, or toward the operators side of the machine, from whence the free thread end is designated 25E (see Fig. '7)

slide in its opening. Obviously the needle and its slide are reciprocable in horizontal plane from left to right and vice-versa, the point of Vtheneedle 2H designates the humped part of the goods v being stitched, whether said goods be single, multiple thickness or hemmed. To the right side of Vaperture 20 the base 9 is sloped or beveled to the directed toward the right and 'traverses a quajdrangular opening 29 (see Figs.v 1,1/7,v and 14) in the base 9. It will be understood at this point that a piece of woven material 2, to be blind-stitched` is fed.

` mainly an arm extending over and across the neerearwardly under the base 9 and between it and the cloth plate by means well known in the artA or the means disclosed in my allowed application specified. In Figs. 6 and8-l3 inclusive I have shown goods 2 folded upon itself to make a hem and forming a folded edge 2E which edge part it 'will be assumed, for illustrative purposes, is going to be blind stitched, a row of said type, of stitches being shownin enlarged scale in Fig. 6. d rlhe cloth is placed initiallyunder the base 9 with its edge 2E extending rearwardly (see Fig. 1) and guided bythe downwardrnger 22F of a 'guide plate 2 2 fixed on: the rail I8 nearest the operator (see Figs. 1, 2., and 3) saidyedge 2E traversing the opening Z of base l9 `where the goods are humped or ridged upwardly in inverted Vgform by a vertically reciprocable plunger 23 with a tapered upperV extremity A,of unique con:r struction (hereinafter described) and arranged to project the goods upwardly in inverted V form and in the path'A of the threaded needle I9 so that the goods are penetrated` at the apexnof said V form in such a manner that the under-side ofthe goodsdoesnot-show the thread.V Y ,p f

lIn Fig. therhumpedrupgo'ods (on upprgend of plunger) are distinctly shown and` line Y|91! indicatesthe horizontal path of needle movement. The needle `penetrates the goods twice, at theleft and right of tapered end of the plunger, said endl part ofH the plunger in this case having certainl advantageous features of construction, as follows: 23A is a central coreror stem of said plunger having. a limited butA continuous upwardly bearingf action Ybecause of a spring 24 under it and within Vthe bore of the plunger. Said core isl tapered upwardly at its upper end to conform to, the tapered shape of the end of the plunger. The top edge of the tapered tip is of course central and in the Ypath of the needle in such position that the point of the needle will contact it lightly in agroove 23G and the needle rides said groove while reciprocating in and out Yof the goods at the bulge in the latter caused'by the said tapered end. The importancer of this feature will be morereadily understood hereinafter in conjunction with the description of the process 'in making blind stitches. The timing and vertical action of the plunger is identical with the means used inmy previous application it being readily seenfthat the humping of the goods for needle penetration takes placewhile the cloth is heldI stationary between the .base Banda cloth plate 4 and movementof the goods rearwardly takes place only when the needle has been drawn out (to the left)Y clear of the cloth.

InFigs. 1, 7, and. 14, 26 designates an aperture in thev left end cross member of needle carrier l'l` right-to bear down on the cloth as at 2l (in Figs. 5 and 14) in conformity with the slope of the right side of the tapered upper end of the plunger.

28 is a'transversely directed thread guide secured paralleli to the rear rail I8 and comprising dle slide, said latter arm having a notch 28N (Fig. 1) at its right side through which thefeed-in thread is guided to the Iaperture 26. y

In Figs. l, 2, 7, and 9 to 14 inclusive, 29 designates a iiat metal plate member in vertical plane, elongated horizontally and pivotally retained at its right hand end as on a pin 30 in front of the vertical arm of bracket I6. The left end of said member is formed with a downward oifset and curvednger 29F tapered toward the left and its point directed upwardly, said point oscillatable vertically and horizontally with its pointmovingvertically into and out of a position alongside 'of the needle. This iinger member will vlfiereinafter be called the looper. d f v IntermediateA the ends of said looper is xedja forwardly projecting pin 3| which may comprise a roller riding the'humped up edge or camface 32F of a` vertically disposed plate 32 fixedlals at 33 on the front rail I8'. Said cam member is'distinctly shown in Figs. 1, 2, 3, and 7 in full lines, andin Figs.. 8 to V13 inclusive the cam .face`32F is shown dotted only, to more clearly reveal the function of the looper, it being understood that said cam face is parallel to and adjacent thev front sideof the looper.

At this point the mechanical action of my'd`evice up to the stitch forming needle action islas follows :r The vertical reciprocating movement of needle bar l, through crosshead Il engaging'4 in angular slot IUS imparts silent oscillating movement to the main lever l. This in turn, through link 2| and bracket I6 (fixed on needle carrier) impartshorizontal reciprocating movement to the needle carrier and needle I9 derives necessary stroke for penetration of cloth humped upwardly in its path and in the aperture 20 of base 9.

' The reciprocating movementV of bracket lr6 carrying lthe looper gives the latter corresponding movement from left to right and vice versa,f which movement causes the looper to ride on and' horizontally, said raising and loweringr of linger 29F-providing certainY thread engaging and'c'lis-k engaging actions whichV formfthread loops on top ofthe cloth between each'cloth penetrating dac` tion of the needle, the finger action andneedle action cofordinated'or timed for the purpose, as

will'now bedescribed.

'Referring particularly to Figs. 7 to. 13 inclusive, Fig. 7 is a-perspective viewofl the stitching means' particularly (omitting the parts providingV recipl rocating action of the needle carrier) and siro-wing the; needle carrier'frame Ain extreme left position` and thel needle threaded tostart stitching action 4its 'rstmo'vement being L of course to the right, the `needle at this time positioned with its point in spaced Arelation to` where it will `enter the cloth as at 34 in 'Fig..8,` 35` designating where it will `emerge 'frcmthe goods.

When the needle is threaded asinFigs. 7 and 8, thevlooper S29-isr .at the extreme left position with its `linger ZSF. downparallel to and alongside of the pointed end' of the needle. Atl this .time the cloth is pressed between basev 9 and thecloth plate 4 andhumped in aperture 20 inthe path off theneedle. i

Downward actionofneedle bar through the link means'describedimparts movement of the needle carrierto the right,-the needle penetrating vthe .clothes shown in Fig.;9, two bights of thread .being drawnltlirough theV goods. When `the needle reaches. this extreme right position the looperjhas'r'idden over-the hump of `cam face 32F and its finger is again .positioned alongside of theA exposed needle point in-such position that when the needlestarts to move back (to left),

the tip of finger `29Fenters upwardly `between the adjacent bightfof the thread (to the left of the needle eye) and the needle. At this time the looperl` is starting to rise on the cam face 32F and the nger 29E carries the thread and draws it upwardly in the form of an elongated loop designated 25L in Fig. l0. Fig. 11 illustrates the needle emerging (toward the left) out of the cloth, looper 29 coming down on the left slope o-f the cam face still drawing out andy enlarging the loop 25L and bearing said loop toward the upper face of the cloth. p

As soon as the needle is completely free of the cloth the feed bar 8 of the sewing machine functions to move the goods rearwardly one step (as from A to B in Fig. 12). The looper, still holding the thread on its finger causes the thread to be drawn out into an elongated loop 25L (Fig. 12) and as the needle reaches its extreme left position the linger brings the thread loop down on and over the cloth in such manner that when the needle again goes into penetrating. action it goes through the loop 25L (see Fig. 13).

In recedinQV from the cloth, thread extends from the aperture where the needle first entered to the front side of the needle eye, this part of the thread designated 25E in Fig. 12 becoming a single strand extending from said rst point of entry to the second point of entry and lies on the lower part of loop 25L when the needle makes each succeeding penetration.

In Fig. 13 the needle is shown making second penetration as the looper nger 29F moves to right and the loop rides off the point of the finger as the latter moves downwardly to Vthe right to assume the next pre-loop forming position shown in Fig. 9.

In Figs. 1, 7, and 14, 36 is a plate fixed on the iront rail I8 and having a tapered arm 36F within opening 20 and pointed rearwardly therein. IThe looper iinger rides over this finger both ways and the needle reciprocates under it. The main purpose of this finger is to engage and guide the thread forming each loop 251'.. and prevents undue jumping or misplacement of the thread while stitching as above described. The shape of said member 36 and its finger 36E may be varied considerably.

An important feature of my invention is the dual action of the plunger 23. With the construction oi the main body of the plunger as in my previous application it bears upwardly yieldably. .As show-nin Fig. 5 one shoulder (tothe left of the tapered tip) bears upwardly toward 4underside of the presser ioot.,` This shoulder andthe top" edge of. the plunger are simultaneously -positioned vertically in transverse. relation tol thepathof the needle according to the thickness of the' cloth. The yieldable part of the plunger has previously beendescribed. Obviously thejvarious thicknesses of cloth modifies the vertical position-of the presser foot.. 4The plunger is reciprocated preferably by aroller actuated bythe feed bar'8 of the sewing machine (Fig. 3)` in coordinated timing relative to the latter as setforth in my previous application.

The modification Fig. l5 reveals in place of lever I0,fa beam lever 10,pivoted on pin 3, the upper end of said lever vconnected. by means of a-link 'Hto the block l2 of the needle bar. The lower end of said levier T0 is pivotally connected to the left `end of the link 2l, at I4. The dotted lowermost position of block l2 and corresponding positionof link 1I moves the needlecarriage to extreme rightposition. 'Ihe full line showing of the parts j-ust described shows theextreme left position ofthecarrlage, Athe 4latter `beingwwhen the needle is fully retracted 'or clear of the goods. In'other words this modified construction embodies simply a plain beam lever 'lll with positive link connection to the needle bar 'I and direct connection to the link member 2l of the carriage. A beam lever and link are substituted for the L-shaped lever l0. There is no sliding contact as in slot IDS but a'positive silent link motion which has proven highly efcient particularly for high speed machines.

I claim:

1. A blind stitch attachment for sewing machines and comprising a main frame of L shape in cross section the upright arm thereof detachably securable to the presser foot bar of a sewing machine, the base thereof comprising an elongated horizontal plate longitudinal of the sewing machine head, a needle holding frame retained for reciprocable movement on said base with the needle pointed toward the center of the base, an L shaped lever pivotally mounted on said arm and means connecting an arm thereof with the needle bar of the machine to impart vertical oscillating movement to said lever, the lever pivoted at the extremityof the other arm, means intermediate said L lever and the needle frame to impart horizontal reciprocating movement of the latter, said presser foot base provided with a central aperture traversed by the needle during reciprocating action, said base positioned directly over the cloth plate of the sewing machine and adaptable to bear down on cloth fed rearwardly between the base and said cloth plate, means coordinated mechanically with the cloth feeding means of the sewing machine for humping the cloth upwardly in the path of the needle in an inverted V form to provide double penetration of the goods by the needle projected horizontally through said V formation of the cloth and means for regulating the extent of said upward projection of the cloth humping means.

2. The structure specified in claim 1 and means for longitudinal guidance of the needle frame comprising a pair of fixed guide rails on the base of the presser foot member, said needle holder comprising an elongated open frame closed at the left endand carrying means for removably retaining a needle in parallel relation to and between said guide rails and pointed toward the the upright arm of the said bracket fixed on the ,f

needle frame;

3. The structure specified in claim .1, and a tapered finger member securedon the -base of the presser foot, the linger part thereof projecting rearwardlyin the said central aperture over the cloth and comprising ya thread loop retaining member and spreader.

4. A blind stitchmechansm for. sewing machines- Vhaving a verticallygreciprocable presser foot bar, la vertically reciprocable needle bar,

a clothplate and table, ini common plane therefA below,l `a reciprocable eedbar and means` actuated thereby jto' contact and feed the cloth rearwardly under theA needle'bar,` the `-action of said feed barsynchronized "with relation to the needle bar; saidA mechanismH comprising a presser `foot member of L-shape and removably xed on the vpresser, foot bar With'its vertical arm, its lower ypart comprising a :dat foot pieceielongated in direction .transversely of theclothmcvement, a needle carryingframe reciprocably retained on said foot piece and removably retaining a needle therein in horizontalplane with its point directed toward the center of ,the frame, means intermediate the needle bar and said needle frame for imparting Ahorizontal reciprocating movement to the needle and itsHframesaid foot piece providedwith an aperturein its central part and traversed by the needle, a vertically reciprocable plunger mounted under the cloth plate and having an ,upwardly tapering end part terminating in a diametrical edge to engage Vcloth fed under the presser foot and to press it upwardly in inverted y-form, in the path of the needle, to pro-,-

'vide for double penetration of the cloth, said initial contact of, the needle point and yieldable during subsequent movement of the needle in its reciprocating stitching action. i

- JOSEPH F, ARVER. 

